Coated article with low-e coating having titanium oxide layer and/or nicr based layer(s) to improve color values and/or transmission, and method of making same

ABSTRACT

Certain example embodiments of this invention relate to a coated article including a low-E coating. In certain example embodiments, a titanium oxide inclusive bottom layer stack and/or a NiCr-based layer(s) are designed to improve b* coloration values and/or transmission of the coated article. These layer stack portions also are advantageous in that they permit a double-silver coated article to achieve (i) an LSG value (T VIS /SHGC) of at least 2.0, (ii) an SHGC value of no greater than 35%, more preferably no greater than 33, 32 or 30%, and (iii) a U-value (BTU h −1  ft −2  ° F. −1 ) (e.g., x= 12  mm) of no greater than 0.30, more preferably no greater than 0.28 or 0.25. In certain example embodiments, the titanium oxide based layer may be an interlayer provided in a bottom portion of the layer stack between first and second layers comprising silicon nitride. Coated articles according to certain example embodiments of this invention may be used in the context of insulating glass (IG) window units, other types of windows, or in any other suitable application.

Certain example embodiments of this invention relate to a coated articleincluding a low-E coating. In certain example embodiments, a titaniumoxide inclusive bottom layer stack and a NiCr-based layer(s) aredesigned to improve b* coloration values and/or transmission of thecoated article. These layer stack portions also are advantageous in thatthey permit a double-silver coated article to achieve (i) an LSG value(T_(VIS)/SHGC) of at least 2.0, (ii) an SHGC value of no greater than35%, more preferably no greater than 33, 32 or 30%, and (iii) a U-value(BTU h⁻¹ ft⁻² ° F.⁻¹) (e.g., x=12mm) of no greater than 0.30, morepreferably no greater than 0.28 or 0.25. In certain example embodiments,the titanium oxide based layer may be an interlayer comprising titaniumoxide provided in a bottom portion of the layer stack, between first andsecond layers comprising silicon nitride, and located between the glasssubstrate and the bottom infrared (IR) reflecting layer comprisingsilver. Coated articles according to certain example embodiments of thisinvention may be used in the context of insulating glass (IG) windowunits, monolithic applications, laminated windows, other types ofwindows, or in any other suitable application such as in electronicdevices.

BACKGROUND OF THE INVENTION

Coated articles are known in the art for use in window applications suchas insulating glass (IG) window units, vehicle windows, and/or the like.

In certain situations, designers of coated articles often strive for acombination of desirable visible transmission, desirable color values,high LSG (T_(VIS)/SHGC) values, low emissivity (or emittance), low SHGCvalues, and low sheet resistance (R_(s)). High visible transmission forexample may permit coated articles to be more desirable in certainwindow applications, whereas low-emissivity (low-E), low SHGC, high LSG,and low sheet resistance characteristics permit such coated articles toblock significant amounts of IR radiation so as to reduce for exampleundesirable heating of vehicle or building interiors.

U.S. Patent Document 2005/0202254, commonly owned and herebyincorporated herein by reference, discloses a coated article having thefollowing layers on a glass substrate, from the glass substrateoutwardly.

Layer

Glass Substrate

TiO₂

Si₃N₄

ZnO

Ag

NiCrO_(x)

SnO₂

Si₃N₄

SnO₂

ZnO

Ag

NiCrO_(x)

SnO₂

Si₃N₄

While the aforesaid coated article is heat treatable, and has manydesirable and good characteristics, it does have one or more of thefollowing problems: (a) its LSG values (T_(VIS)/SHGC) being too low, and(b) its SHGC values being too high.

U.S. Patent Document 2008/0070044, commonly owned herewith. disclosesanother coated article. While the aforesaid coated article is heattreatable, and has many desirable and good characteristics, it does haveone or more of the following problems: (a) its LSG values (T_(VIS)/SHGC)being too low, (b) its SHGC values being too high, and (c) undesirableb* value.

In certain example embodiments of this invention, one or more of theabove-identified problems can be solved. While certain preferredembodiments solve all of the above problems, other embodiments of thisinvention may only solve one or two of the above-identified problems.

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

In certain example embodiments of this invention, a coated articleincluding a low-E coating is provided, and/or a method of making thesame. In certain example embodiments, a color tuning titanium oxideinclusive bottom layer stack and a NiCr-based layer(s) is/are designedto improve b* coloration values and/or transmission of the coatedarticle. These layer stack portions also are advantageous in that theypermit a double-silver coated article to achieve one or more of: (i) anLSG value (T_(VIS)/SHGC) of at least 2.0, (ii) an SHGC value of nogreater than 35%, more preferably no greater than 33, 32 or 30%, and(iii) a U-value (BTU h^(−1 ft) ⁻² ° F.⁻¹) (e.g., x=12mm) of no greaterthan 0.30, more preferably no greater than 0.28 or 0.25. Thus, the useof this layer(s) provides for color tuning advantages as well asimproved optical and SHGC advantages in the coated article. In certainexample embodiments, the titanium oxide based layer may be an interlayercomprising titanium oxide provided in a bottom portion of the layerstack, between first and optionally second layers comprising siliconnitride or the like, and located between the Wass substrate and thebottom infrared (IR) reflecting layer comprising silver. Coated articlesaccording to certain example embodiments of this invention may be usedin the context of insulating glass (IG) window units, other types ofwindows, or in any other suitable application. In certain exampleembodiments, the titanium oxide based color tuning layer is from about40-400 Å thick, more preferably from about 50-200 Å thick, and mostpreferably from about 70-120 Å thick.

In certain example embodiments, it has also been surprisingly found thatthinning one or both NiCr based layers in this coating helps to achievea combination of a lower transmissive b* value and higher visibletransmission. In certain example embodiments, one or both of the NiCrbased contact layers is from about 4-14 Å thick, more preferably fromabout 4-12 Å thick, and most preferably from about 6-11 Å thick. It isbelieved that the higher visible transmission and the improved b* valuesmay be a result of a combination of the thin NiCr based layer(s) and thetitanium oxide based layer. This higher visible transmission andacceptable b* combination is especially desirable, because it permitsmore silver to be added (thicker silver based layer(s)) which increasesLSG without sacrificing optical performance. This combination therebyresults in the surprisingly high LSG values achievable by this coating.

In certain example embodiments of this invention, there is provided ainsulating glass (IG) window unit including a coated article including acoating supported by a glass substrate, the coating comprising: firstand second infrared (IR) reflecting layers, wherein said IR reflectinglayers are spaced apart from one another by a plurality of dielectriclayers, and wherein the first IR reflecting layer is located closer tothe glass substrate than is the second IR reflecting layer; a bottomdielectric stack provided between the first IR reflecting layer and theglass substrate, wherein the bottom dielectric stack comprises in adirection moving away from the glass substrate a first dielectric layer,a layer comprising titanium oxide and/or niobium oxide, and a seconddielectric layer, and wherein the layer comprising titanium oxide and/orniobium oxide is located between and directly contacting the first andsecond dielectric layers; a contact layer comprising metal and/or metaloxide located over and directly contacting at least one of the IRreflecting layers comprising silver, wherein the contact layer is fromabout 4-14 Å thick; and wherein the glass substrate is spaced apart fromanother glass substrate in the IG window unit, and wherein the IG windowunit has an LSG value (T_(VIS)/SHGC) of at least 2.0, and a visibletransmission of at least about 60%.

In certain other example embodiments of this invention, there isprovided a method of making an insulating glass (IG) window unitincluding a coated article including a coating supported by a glasssubstrate, the method including forming the coating on the glasssubstrate comprising the steps of: forming first and second infrared(IR) reflecting layers comprising silver on the glass substrate, whereinsaid IR reflecting layers are spaced apart from one another by at leastone dielectric layer that is located therebetween, and wherein the firstIR reflecting layer is located closer to the glass substrate than is thesecond IR reflecting layer; forming a bottom dielectric stack providedbetween the first IR reflecting layer and the glass substrate via atleast sputtering, wherein the bottom dielectric stack comprises movingaway from the glass substrate a first layer comprising silicon nitride,a layer comprising titanium oxide, and optionally a second layercomprising silicon nitride, and wherein the layer comprising titaniumoxide is located between and directly contacting the first and secondlayers comprising silicon nitride; and forming a contact layercomprising NiCr located over and directly contacting at least one of theIR reflecting layers comprising silver, wherein the contact layercomprising NiCr is from about 4-14 Å thick.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a coated article according to anexample embodiment of this invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Coated articles herein may be used in applications such as IG windowunits, vehicle windows, residential windows, and/or any other suitableapplication that includes glass substrate(s). Certain exampleembodiments of this invention relate to a coated article including alow-E coating. In certain example embodiments, a titanium oxideinclusive bottom layer stack and a NiCr-based layer(s) are designed toimprove b* coloration values and/or transmission of the coated article.These layer stack portions also are advantageous in that they permit adouble-silver coated article to achieve (i) an LSG value (T_(VIS)/SHGC)of at least 2.00, (ii) an SHGC value of no greater than 35% (or 0.35),more preferably no greater than 33, 32 or 30% (or 0.30), (iii) a U-value(BTU h⁻¹ ft⁻² ° F.⁻¹) (e.g., x=12 mm) of no greater than 0.30, morepreferably no greater than 0.28 or 0.25, and (iv) a visible transmission(III. C. 2 degree) of at least about 60%, more preferably of at leastabout 65%, even more preferably of at least about 70% or 72%. The abovecharacteristics are provided when the coated article is in a monolithicform, or in the context of an IG (insulating glass) window unit. Incertain example embodiments, the titanium oxide based layer may be aninterlayer comprising titanium oxide provided in a bottom portion of thelayer stack between first and second layers comprising silicon nitride,and located between the glass substrate and the bottom infrared (IR)reflecting layer comprising silver. Coated articles according to certainexample embodiments of this invention may be used in the context ofinsulating glass (IG) window units, monolithic applications, laminatedwindows, other types of windows, or in any other suitable applicationsuch as electronic devices. In certain example embodiments of thisinvention, the coating includes a double-silver stack, although thisinvention is not so limited in all instances.

For example, in certain example embodiments of this invention, heattreated or non-heat treated coated articles having multiple IRreflecting layers (e.g., two spaced apart silver based layers) arecapable of realizing a sheet resistance (R_(s)) of less than or equal to3.0 (more preferably less than or equal to 2.5, even more preferablyless than or equal to 2.1, and most preferably less than or equal to2.0, 1.9 or 1.8 ohms/square).

FIG. 1 is a side cross sectional view of a coated article according toan example non-limiting embodiment of this invention. The coated articleincludes substrate 1 (e.g., clear, green, bronze, or blue-green glasssubstrate from about 1.0 to 10.0 mm thick, more preferably from about1.0 mm to 3.5 mm thick), and low-E coating (or layer system) 30 providedon the substrate 1 either directly or indirectly. The coating (or layersystem) 30 includes, for example: bottom dielectric silicon nitridelayer 3 which may be Si₃N₄, of the Si-rich type for haze reduction, orof any other suitable stoichiometry silicon nitride in differentembodiments of this invention, color tuning titanium oxide based layer 4(e.g., of or including TiO₂ or the like), optional additional dielectricsilicon nitride layer 5 which may be Si₃N₄, of the Si-rich type for hazereduction, or of any other suitable stoichiometry silicon nitride, firstlower contact layer 7 (which contacts bottom IR reflecting layer 9),first conductive and preferably metallic infrared (IR) reflecting layer9, first upper contact layer 11 (which contacts layer 9), dielectriclayer 13 (which may be deposited in one or multiple steps in differentembodiments of this invention), another silicon nitride based and/orinclusive layer 14, tin oxide inclusive based and/or inclusiveinterlayer 15, second lower contact layer 17 (which contacts IRreflecting layer 19), second conductive and preferably metallic IRreflecting layer 19, second upper contact layer 21 (which contacts layer19), dielectric layer 23, and finally protective dielectric layer 25.The “contact” layers 7, 11, 17 and 21 each contact at least one IRreflecting layer (e.g., layer based on Ag). The aforesaid layers 3-25make up low-E (i.e., low emissivity) coating 30 that is provided onglass or plastic substrate 1.

In monolithic instances, the coated article includes only one glasssubstrate I as illustrated in FIG. 1. However, monolithic coatedarticles herein may be used in devices such as laminated vehiclewindshields, IG window units, and the like. As for IG window units, anIG window unit may include two spaced apart glass substrates. An exampleIG window unit is illustrated and described, for example, in U.S. PatentDocument No. 2004/0005467, the disclosure of which is herebyincorporated herein by reference. An example IG window unit may include,for example, the coated glass substrate 1 shown in FIG. 1 coupled toanother glass substrate via spacer(s), sealant(s) or the like, with agap being defined therebetween. This gap between the substrates in IGunit embodiments may in certain instances be filled with a gas such asargon (Ar). An example IG unit may comprise a pair of spaced apart clearglass substrates each about 3-4 mm thick, one of which is coated with acoating 30 herein in certain example instances, where the gap betweenthe substrates may be from about 5 to 30 mm, more preferably from about10 to 20 mm, and most preferably about 16 mm. In certain exampleinstances, the coating 30 may be provided on the interior surface ofeither substrate facing the gap. In certain example embodiments, thecoating 30 is provided on the non-tin side (in the context of floatglass) of the glass substrate of an IG unit closest to the sun; i.e., onthe #2 surface of the IG unit.

Titanium oxide based layer 4 is, in certain example embodiments of thisinvention, located between and contacting dielectric layers 3 and 5. Thetitanium oxide based layer 4 is advantageous in that it is useful forcolor tuning, as it allows the transmissive b* value of the coatedarticle to be maintained at a desirable level (fairly low)—this is notachieved by using only silicon nitride at any reasonable thickness withno titanium oxide based layer 4. In certain example embodiments, niobiumoxide may be used instead of or in addition to titanium oxide for or inhigh index layer 4. Thus; layer 4 whether of or including titanium oxideand/or niobium oxide preferably has a refractive index (n) of at leastabout 2.3 in certain example embodiments of this invention. The titaniumoxide based layer 4 is also advantageous in that it allows realizationof a desirable high reflective glass side b* value (less blue outsidereflectance) for the coated article, and also results in a highervisible transmission of the coated article. In certain exampleembodiments, the titanium oxide based layer 4 is from about 40-400 Åthick, more preferably from about 50-200 Å thick, and most preferablyfrom about 70-120 Å thick.

In certain example embodiments, the process of making the TiO_(x) basedlayer 4 can achieve a higher dynamic deposition rate (DDR). Inparticular, O₂ gas flow during sputtering of the Ti based target(s) canbe decreased to about 0.4 to 0.65, more preferably from about 0.55 to0.65, from the typical 0.7 ml/kW. Using a gas flow lower than that isnot desirable, because DDR absorption can increase too much, and 0.7ml/kW and higher is undesirable in that the layer becomes a linespeedbottleneck in the manufacturing process.

In certain example embodiments, an interlayer 15 comprising tin oxide orthe like may be provided under an upper infrared (IR) reflecting layer19 and in particular between respective layers comprising siliconnitride 14 and zinc oxide 17. It has been found that the use of such atin oxide inclusive interlayer (or adhesion layer) 15 results insignificantly improved thermal stability, mechanical durability (e.g.,scratch resistance), and haze characteristics. For example, with regardto thermal stability, it has been found that the use of such a tin oxideinclusive interlayer 15 results in a coated article which is capable ofrealizing one or more of: (a) less visible transmission shift due toheat treatment, (b) higher visible transmission following heattreatment; (c) less shifting of certain color value(s) due to heattreatment, (d) substantially neutral coloration following heattreatment; (e) more stable, or even decreasing, sheet resistance due toheat treatment, (f) lower sheet resistance and thus lower emissivityfollowing heat treatment, and/or (g) improved haze characteristicsfollowing heat treatment. It has also been found that the provision ofthis tin oxide inclusive interlayer 15 is also capable of significantlyimproving mechanical durability and haze characteristics of the coatedarticle, compared to if the layer were not present. These surprisinglyresults, which in certain example instances are associated with the useof the combination layer stack portion of glass . . .Si_(x)N_(y)/SnO²)/ZnO/Ag . . . , are highly advantageous, sincemechanical durability, higher visible transmission, lower emissivity,lower sheet resistance, reduced haze, and/or improved thermal stabilityare typically desired features in coated articles.

Dielectric layers 3, 5 and 14 may be of or include silicon nitride incertain embodiments of this invention. Silicon nitride layers 3, 5 and14 may, among other things, improve heat-treatability of the coatedarticles, e.g., such as thermal tempering or the like. The siliconnitride of layers 3, 5 and/or 14 may be of the stoichiometric type(i.e., Si₃N₄), or alternatively of the Si-rich type in differentembodiments of this invention. For example, Si-rich silicon nitride 3(and/or 5, 14) combined with zinc oxide and/or tin oxide under a silverbased IR reflecting layer may permit the silver to be deposited (e.g.,via sputtering or the like) in a manner which causes its sheetresistance to be lessened compared to if certain other material(s) wereunder the silver. Moreover, the presence of free Si in a Si-rich siliconnitride inclusive layer 3 (5 and/or 14) may allow certain atoms such assodium (Na) which migrate outwardly from the glass 1 during HT to bemore efficiently stopped by the Si-rich silicon nitride inclusive layerbefore they can reach the silver and damage the same. Thus, it isbelieved that the Si-rich Si_(x)N_(y) can reduce the amount of damagedone to the silver layer(s) during HT in certain example embodiments ofthis invention thereby allowing sheet resistance (R_(s)) to decrease orremain about the same in a satisfactory manner. Moreover, it is believedthat the Si-rich Si_(x)N_(y) in layer 3 and/or 5 can reduce the amountof damage (e.g., oxidation) done to absorbing layer 4 during HT incertain example optional embodiments of this invention. It is alsopossible that a zirconium oxide and/or nitride layer (not shown) beprovided over top of the top silicon nitride based layer 25 in certainexample embodiments of this invention, as a protective overcoat layer.

In certain example embodiments, when Si-rich silicon nitride is used inlayer 3, 5 and/or 14, the Si-rich silicon nitride layer as deposited maybe characterized by Si_(x)N_(y) layer(s), where x/y may be from 0.76 to1.5, more preferably from 0.8 to 1.4, still more preferably from 0.85 to1.2. Moreover, in certain example embodiments, before and/or after HTthe Si-rich Si_(x)N_(y) layer(s) may have an index of refraction “n” ofat least 2.05, more preferably of at least 2.07, and sometimes at least2.10 (e.g., 632 nm) (note: stoichiometric Si₃N₄ which may also be usedhas an index “n” of 2.02-2.04). In certain example embodiments, it hassurprisingly been found that improved thermal stability is especiallyrealizable when the Si-rich Si_(x)N_(y) layer(s) as deposited has anindex of refraction “n” of at least 2.10, more preferably of at least2.20, and most preferably from 2.2 to 2.4. Also, the Si-rich S_(x)N_(y)layer in certain example embodiments may have an extinction coefficient“k” of at least 0.001, more preferably of at least 0.003 (note:stoichiometric Si₃N₄ has an extinction coefficient “k” of effectively0). Again, in certain example embodiments, it has surprisingly beenfound that improved thermal stability can be realized when “k” for theSi-rich Si_(x)N_(y) layer(s) is from 0.001 to 0.05 as deposited (550nm). It is noted that n and k tend to drop due to heat treatment. Anyand/or all of the silicon nitride layers discussed herein may be dopedwith other materials such as stainless steel or aluminum in certainexample embodiments of this invention. For example, any and/or allsilicon nitride layers discussed herein may optionally include fromabout 0-15% aluminum, more preferably from about 1 to 10% aluminum, incertain example embodiments of this invention. The silicon nitride maybe deposited by sputtering a target of Si or SiAl in certain embodimentsof this invention. Oxygen may also be provided in certain instances inthe silicon nitride layers.

Infrared (IR) reflecting layers 9 and 19 are preferably substantially orentirely metallic and/or conductive, and may comprise or consistessentially of silver (Ag), gold, or any other suitable IR reflectingmaterial. IR reflecting layers 9 and 19 help allow the coating to havelow-E and/or good solar control characteristics. The IR reflectinglayers may, however, be slightly oxidized in certain embodiments of thisinvention. In certain example embodiments, the upper IR reflecting layer19 is significantly thicker than the lower IR reflecting layer 9 (e.g.,by at least about 15 or 25 Å).

The upper contact layers 11 and 21 may be of or include nickel (Ni)oxide, chromium/chrome (Cr) oxide, or a nickel alloy oxide such asnickel chrome oxide (NiCrO_(x)), or other suitable material(s), incertain example embodiments of this invention. The use of, for example,NiCr in these layers (11 and/or 21) allows durability to be improved.The NiCr of layers 11 and/or 21 may be fully oxidized in certainembodiments of this invention (i.e., fully stoichiometric), oralternatively may only be partially oxidized. In certain instances, theNiCrO_(x) layers 11 and/or 21 may be at least about 50% oxidized, butnot fully oxidized in the final product. Contact layers 11 and/or 21(e.g., of or including an oxide of Ni and/or Cr) may or may not beoxidation graded in different embodiments of this invention. Oxidationgrading means that the degree of oxidation in the layer changesthroughout the thickness of the layer so that for example a contactlayer may be graded so as to be less oxidized at the contact interfacewith the immediately adjacent IR reflecting layer than at a portion ofthe contact layer(s) further or more/mast distant from the immediatelyadjacent IR reflecting layer. Descriptions of various types of oxidationgraded contact layers are set forth in U.S. Pat. No. 6,576,349, thedisclosure of which is hereby incorporated herein by reference, althoughother types of oxide grading may also be performed for these layers.Contact layers 11 and/or 21 (e.g., of or including an oxide of Ni and/orCr) may or may not be continuous in different embodiments of thisinvention across the entire IR reflecting layer. While the contactlayers 11, 21 are of or include Ni and/or Cr in preferred embodiments,it is possible that other materials such as titanium oxide or the likemay be used for these layers.

In certain example embodiments, it has also been surprisingly found thatthinning one or both NiCr based layers 11 and/or 21 helps to achieve acombination of a lower transmissive b* value and higher visibletransmission T_(VIS). In certain example embodiments, one or both of theNiCr based contact layers 11 and/or 21 is from about 4-14 Å thick, morepreferably from about 4-12 Å thick, and most preferably from about 5-8 Åthick. It is believed that the higher visible transmission and theimproved b* values may be a result of a combination of the thin NiCrbased layer(s) 11 and/or 21 and the titanium oxide based layer 4. Thishigher visible transmission and acceptable b* combination is especiallydesirable, because it permits more silver to be added (thicker silverbased layer(s) 9 and/or 19) which increases LSG of the coated articlewithout sacrificing optical performance. This combination therebyresults in the surprisingly high LSG values achievable by this coating.In certain example embodiments, one or both of the NiCr based layers 11and 21 may be originally sputter-deposited in metallic or substantiallymetallic form (not significantly oxided). Then, they may becomepartially oxided during sputter-deposition of the overlying tin oxide orother metal oxide based layer(s) 13, 23. This may result in anoxidation, graded and/or substoichometric oxidation of the NiCr basedlayer(s) 11 and/or 21.

Dielectric layer 13 may be of or include tin oxide in certain exampleembodiments of this invention. However, as with other layers herein,other materials maybe used in different instances.

Lower contact layers 7 and/or 17 in certain embodiments of thisinvention are of or include zinc oxide (e.g., ZnO). The zinc oxide oflayers 7 and 17 may contain other materials as well such as Al (e.g., toform ZnAlO_(x)). For example, in certain example embodiments of thisinvention, one or more of zinc oxide layers 7, 17 may be doped with fromabout 1 to 10% Al, more preferably from about 1 to 5% Al, and mostpreferably about 1 to 4% Al. In certain example embodiments, the lowerzinc oxide based contact layer 7 is thinner than the upper zinc oxidebased contact layer 17, by at least about 10 Å, more preferably by atleast about 15 or 20 Å. It has been found that this improves colorationand/or transmission of the coating.

Interlayer 15 of or including tin oxide is provided under IR reflectinglayer 19 so as to be located between silicon nitride layer 14 and zincoxide layer 17. Surprisingly, as explained above, it has been found thatthe use of such a tin oxide inclusive interlayer 15 results in numerousimprovements compared to a situation where the layer is not provided.For example, it has been found that the use of such a tin oxideinclusive interlayer 15 results in a coated article which is capable ofrealizing: (a) less visible transmission shift due to heat treatment,(b) higher visible transmission following heat treatment; (c) lessshifting of certain color value(s) due to heat treatment, (d)substantially neutral coloration following heat treatment; (e) morestable, or even decreasing, sheet resistance due to heat treatment, (f)lower sheet resistance and thus lower emissivity following heattreatment, (g) improved haze characteristics following heat treatment,and/or (h) improved mechanical durability such as scratch resistancebefore and/or after heat treatment. Thus, in certain example embodimentsof this invention, coated articles may be taken to higher temperaturesduring heat treatment and/or for longer times without sufferingundesirable significant transmission drops and/or increases in sheetresistance. In certain alternative embodiments, it is possible to dopethe tin oxide of layer 15 with other materials such as Al, Zn or thelike. Alternatively, other metal oxide(s) may be used for layer 15 incertain instances.

Dielectric layer 23 may be of or include tin oxide in certain exampleembodiments of this invention. However, layer 23 is optional and neednot be provided in certain example embodiments of this invention.Dielectric layer 25, which may be an overcoat in certain exampleinstances, may be of or include silicon nitride (e.g., Si₃N₄) or anyother suitable material in certain example embodiments of thisinvention. Optionally, other layers may be provided above layer 25.Layer 25 is provided for durability purposes, and to protect theunderlying layers during heat treatment and/or environmental use. Incertain example embodiments, layer 25 may have an index of refraction(n) of from about 1.9 to 2.2, more preferably from about 1.95 to 2.05.

Other layer(s) below or above the illustrated coating may also beprovided. Thus, while the layer system or coating is “on” or “supportedby” substrate 1 (directly or indirectly), other layer(s) may be providedtherebetween. Thus, for example, the coating of FIG. 1 may be considered“on” and “supported by” the substrate 1 even if other layer(s) areprovided between layer 3 and substrate 1. Moreover, certain layers ofthe illustrated coating may be removed in certain embodiments, whileothers may be added between the various layers or the various layer(s)may be split with other layer(s) added between the split sections inother embodiments of this invention without departing from the overallspirit of certain embodiments of this invention.

While various thicknesses and materials may be used in layers indifferent embodiments of this invention, example thicknesses andmaterials for the respective layers on the glass substrate 1 in the FIG.1 embodiment are as follows, from the glass substrate outwardly (anexample of the titanium oxide based layer is about 80 angstroms):

Example Materials/Thicknesses; FIG. 1 Embodiment Layer Glass (1-10 mmthick) Preferred Range ({acute over (Å)}) More Preferred ({acute over(Å)}) Example (Å) Si_(x)N_(y) (layer 3) 40-250 Å 125-175 Å 150 Å TiO_(x)(layer 4) 40-400 Å 50-200 Å 70-120 Å Si_(x)N_(y) 40-450 Å 50-150 Å 75 Å(optional layer 5) ZnO_(x) (layer 7) 10-300 {acute over (Å)} 50-85{acute over (Å)} 70 Å Ag (layer 9) 100-180 {acute over (Å)} 125-160{acute over (Å)} 139 Å NiCrO_(x) (layer 11) 4-14 {acute over (Å)} 4-12{acute over (Å)} 5 Å SnO₂ (layer 13) 0-1,000 Å 200-700 Å 585 ÅSi_(x)N_(y) (layer 14) 50-450 {acute over (Å)} 60-100 {acute over (Å)}80 Å SnO₂ (layer 15) 30-250 Å 50-200 Å 109 Å ZnO_(x) (layer 17) 10-300{acute over (Å)} 40-150 {acute over (Å)} 96 Å Ag (layer 19) 130-220{acute over (Å)} 140-200 {acute over (Å)} 169 Å NiCrO_(x) (layer 21)4-14 {acute over (Å)} 4-12 {acute over (Å)} 5 Å SnO₂ (layer 23) 0-750 Å40-200 Å 127 Å Si₃N₄ (layer 25) 0-750 {acute over (Å)} 80-320 {acuteover (Å)} 215 Å

In certain example embodiments of this invention, coated articles hereinmay have the following optical and solar characteristics set forth inTable 2 when measured monolithically (before any optional HT). The sheetresistances (R_(s)) herein take into account all IR reflecting layers(e.g., silver based layers 9, 19).

Optical/Solar Characteristics (Monolithic; no-HT) More MostCharacteristic General Preferred Preferred R_(s) (ohms/sq.): <=2.5 <=2.1<=1.9 (or <=1.8) E_(n): <=0.06 <=0.03 <=0.025 T_(vis) (Ill. C.2°): >=60% >=65% >=70 or 72% a*_(t) (Ill. C. 2°): −6 to +1.0 −5 to −3.0−4.2 to −4.0 b*_(t) (Ill. C. 2°): −2.0 to +4.0 0.0 to 2.0 0.5 to 1.7 L*(Ill. C. 2°): 80-95 84-95 86-89 R_(f)Y (Ill. C., 2 deg.): 1 to 13% 1 to12%  5-9% a*_(f) (Ill. C., 2°): −15.0 to +2.0 −10.0 to −4.0 −7.5 to −6.0b*_(f) (Ill. C., 2°): −30.0 to +4.0 −2.0 to +3.5 0 to 2.0 L* (Ill. C.2°): 30-45 32-41 32-34 R_(g)Y (Ill. C., 2 deg.): 1 to 14% 1 to 13%  5-9%a*_(g) (Ill. C., 2°): −5.0 to 0 −4.0 to −1.0 −3 to −1 b*_(g) (Ill. C.,2°): −14.0 to 0 −13.0 to −7.0 −12 to −8 L* (Ill. C. 2°): 30-40 31-3532-33

Optical/Solar Characteristics (Monolithic; post-HT [e.g., tempered])More Most Characteristic General Preferred Preferred R_(s) (ohms/sq.):<=2.5 <=2.1 <=1.9 (or <=1.8) E_(n): <=0.06 <=0.03 <=0.025 T_(vis) (Ill.C. 2°): >=65% >=70% >=72 or 73% a*_(t) (Ill. C. 2°): −6 to +1.0 −5 to−3.0 −4.8 to −4.4 b*_(t) (Ill. C. 2°): −2.0 to +5.0 0.0 to 4.0 1.0 to3.5 L* (Ill. C. 2°): 80-95 84-95 86-89 R_(f)Y (Ill. C., 2 deg.): 1 to13% 1 to 12%  5-9% a*_(f) (Ill. C., 2°): −15.0 to +2.0 −10.0 to −4.0−7.5 to −6.0 b*_(f) (Ill. C., 2°): −30.0 to +4.0 −4.0 to −0.5 −3.5 to−1.5 L* (Ill. C. 2°): 30-45 32-41 29-32 R_(g)Y (Ill. C., 2 deg.): 1 to14% 1 to 13%  5-9% a*_(g) (Ill. C., 2°): −5.0 to 0 −4.0 to +1.0 −2 to+0.5 b*_(g) (Ill. C., 2°): −14.0 to 0 −13.0 to −8.0 −12 to −9 L* (Ill.C. 2°): 30-40 31-35 30-32

Moreover, in certain example laminated embodiments of this invention,coated articles herein which have been optionally heat treated to anextent sufficient for tempering, and which have been coupled to anotherglass substrate to form an IG unit, may have the following IG unitoptical/solar characteristics, Example IG characteristics may be forexample about 2.3 mm thick glass sheets, an approximate 16 mmgap/spacers, substantially clear glass, and the coating on surface #2.Or alternatively, about 2.5 mm thick clear glass substrates with anapproximate 12.0 mm gap therebetween.

Optical/Solar Characteristics (IG Unit) More Most Characteristic GeneralPreferred Preferred R_(s) (ohms/sq.): <=2.5 <=2.1 <=1.9 (or <=1.8)E_(n): <=0.06 <=0.03 <= 0.025 LSG (T_(vis)/SHGC): >=2.0 >=2.01 >=2.02T_(vis) (Ill. C. 2°): >=60% >=63% >=65 or 66% a*_(t) (Ill. C. 2°): −8 to0 −7 to −2.0 −6.0 to −3.8 b*_(t) (Ill. C. 2°): −2.0 to +4.0 0.0 to 2.20.75 to 1.85 L* (Ill. C. 2°): 80-90 81-87 82-86 Outside Y (Ill. C., 1 to13% 1 to 12% 10-12% 2): a*_(g) (Ill. C., 2°): −7.0 to 0 −5.0 to −1.5−4.0 to −2.0 b*_(g) (Ill. C., 2°): −10.0 to −2.0 −9.0 to −4.5 −8.5 to−5.5 L* (Ill. C. 2°): 30-45 37-42 39-42 Inside Y (Ill. C., 2): 8.5 to14.5% 10 to 12.5% 10.5-12% a*_(f) (Ill. C., 2°): −7.0 to 0 −6 to −3.0 −5to −3.5 b*_(f) (Ill. C., 2°): −7.0 to +4 −5.0 to +2 −4 to +1 L* (Ill. C.2°): 37-47 40-46 43-45 SHGC (% US): <=35% <=33 or 32% <=30% U-Value:<=0.30 <=0.28 <=0.25

The following example is provided for purposes of example only, and isnot intended to be limiting unless specifically claimed.

EXAMPLES

The following Example 1 was made via sputtering on 2.3 mm thick clearglass substrate so as to have approximately the layer stack set forthbelow.

Layer Glass (2.3 mm thick) Thickness ({acute over (Å)}) Si_(x)N_(y)(layer 3) 150 Å TiO₂ (layer 4) 80 Å ZnO_(x) (layer 7) 70 {acute over(Å)} Ag (layer 9) 139 {acute over (Å)} NiCrO_(x) (layer 11) 5 {acuteover (Å)} SnO₂ (layer 13) 585 Å Si_(x)N_(y) (layer 14) 80 {acute over(Å)} SnO₂ (layer 15) 109 Å ZnO_(x) (layer 17) 96 {acute over (Å)} Ag(layer 19) 169 {acute over (Å)} NiCrO_(x) (layer 21) 5 {acute over (Å)}SnO₂ (layer 23) 127 Å Si₃N₄ (layer 25) 215 {acute over (Å)}

The Example above had characteristics in monolithic and in IG unit formwithin the ranges in the right-hand columns of the charts set forthabove.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1-23. (canceled)
 24. An insulating glass (IG) window unit including acoated article including a coating supported by a glass substrate, thecoating comprising: first and second infrared (IR) reflecting layerscomprising silver, wherein said IR reflecting layers are spaced apartfrom one another by at least one dielectric layer that is locatedtherebetween, and wherein the first IR reflecting layer is locatedcloser to the glass substrate than is the second IR reflecting layer,wherein the first IR reflecting layer has a thickness of from about 125to 150 Å, and the second IR reflecting layer has a thickness of fromabout 140 to 200 Å, and wherein the thickness of the second IRreflecting layer is greater than that of the first IR reflecting layer;a bottom dielectric stack provided between the first IR reflecting layerand the glass substrate, wherein the bottom dielectric stack comprisesmoving away from the glass substrate a first layer consistingessentially of silicon nitride, a layer comprising titanium oxide havinga thickness of from about 70-120 Å, and a dielectric layer, and whereinthe layer comprising titanium oxide is located between and directlycontacting the first layer comprising silicon nitride and the dielectriclayer; a center dielectric stack provided between the first and secondIR reflecting layers, wherein the center dielectric stack comprises,moving away from the glass substrate, a first layer comprising tinoxide, a layer comprising silicon nitride, a second layer comprising tinoxide, and a layer comprising zinc oxide, wherein the layer comprisingzinc oxide is located directly under and contacting the second IRreflecting layer; a contact layer comprising Ni and Cr located over anddirectly contacting at least one of the IR reflecting layers comprisingsilver; and wherein the glass substrate is spaced apart from anotherglass substrate in the IG window unit, and wherein the IG window unithas an LSG value (T_(VIS)/SHGC) of at least 2.0, an SHGC value of nogreater than 0.35, a U-value of no greater than 0.30, a visibletransmission of at least about 60%, and wherein the IG window unit hasat least one of: an outside b* color value of from about −8.5 to −5.5,and a transmissive b* color value of from about 0.75 to 1.85.
 25. The IGwindow unit of claim 24, wherein the coated article includes only two IRreflecting layers comprising silver.
 26. The IG window unit of claim 24,wherein said IG unit has a visible transmission of at least about 65%.27. A coated article including a coating supported by a glass substrate,the coating comprising: first and second infrared (IR) reflectinglayers, wherein said IR reflecting layers are spaced apart from oneanother by a plurality of dielectric layers, and wherein the first IRreflecting layer is located closer to the glass substrate than is thesecond IR reflecting layer; a bottom dielectric stack provided betweenthe first IR reflecting layer and the glass substrate, wherein thebottom dielectric stack comprises in a direction moving away from theglass substrate a first dielectric layer consisting essentially ofsilicon nitride, a layer comprising titanium oxide and/or niobium oxide,and a second dielectric layer, and wherein the layer comprising titaniumoxide and/or niobium oxide is located between and directly contactingthe first and second dielectric layers and has a thickness of from about50 to 200 A; a contact layer comprising metal and/or metal oxide locatedover and directly contacting at least one of the IR reflecting layers,wherein the coated article has a visible transmission of at least about60%; and wherein said first and second IR reflecting layers are spacedapart by at least: two spaced apart layers comprising tin oxide, anotherlayer comprising silicon nitride provided between at least the twolayers comprising tin oxide, and a layer comprising zinc oxide.
 28. Thecoated article of claim 27, wherein in the bottom dielectric stack thesecond dielectric layer comprises zinc oxide.
 29. The coated article ofclaim 27, wherein the second dielectric layer comprises silicon nitride.30. The coated article of claim 27, wherein the coated article includesonly two IR reflecting layers.